This invention relates to the art of radiography, and more particularly to a new and improved radiographic imaging apparatus and method optimized for vascular interventions for providing region of interest micro-angiography.
After heart disease and cancer the most significant cause of death in the United States is cerebrovascular disease. The three most common cerebrovascular pathologies are stenoses or narrowing due to vessel degeneration, aneurysms or bulges, and arteriovenous malformations (AVM) which act as short circuits. Hemorrhage and other incidents due to these pathologies or acute thrombogenesis leading to vessel constriction or blockage can lead to stroke resulting in death or devastating effects to the individual who survives.
Often in the past the treatment of choice, although not always possible, was invasive surgery that can carry substantial risks of its own. Image-guided minimally invasive endovascular treatments primarily radiographically guided are becoming increasingly preferred. As these new procedures evolve with smaller and finer catheters and devices, they are placing greater requirements on image quality. Thus, there is a growing requirement for high spatial resolution during endovascular interventions. Clinical decisions for balloon expansion of a stent or attempts to mold the stent within the treated vessel depend upon images with adequate detail. Seeing the spatial relationship between overlapping stents where these may be required is now difficult. Detecting the drift of stents during the placement process is difficult. With newer stents having smaller gauge wire and more complex design it is becoming very difficult to see even the gross shape of the stent let alone to determine the status of the individual segments or wires. As the endovascular devices progress toward treatments of smaller vessels within or beyond the circle of Willis, there will be the additional concern about disturbing or blocking the origin of perforators. These perforators that are 50-500 .mu.m in diameter are often extremely important vessels for specific, key neurological functions, and if blocked can produce devastating deficits in the patient. Perforators seen during invasive micro-surgery typically cannot be visualized by any means during image-guided endovascular procedures. For aneurysm treatment with detachable coils, the thin strands of overlapping coils are typically blurred together into a dense mass with standard DA equipment. Visualization of the detailed shape of the aneurysm and the location and spacing of coil loops could foretell the outcome of the treatment. Finally, for AVM treatment with glue, present images are inadequate in allowing exact evaluation of the filling of small vessels to prevent recurrence.